1. Field of the Invention
The present invention relates to an insertion apparatus having an elongated insertion portion that is inserted into a subject, and an operation portion, wherein the insertion portion is provided with an action portion that acts by operation input from the operation portion.
2. Description of the Related Art
In recent years, insertion apparatuses that are inserted into subjects, endoscopes for example, have been widely used in medical and industrial fields.
An endoscope that is used in the medical field enables observation of an organ in a body cavity by an elongated insertion portion being inserted into the body cavity that is a subject. Further, an endoscope that is used in the medical field enables various kinds of treatments with use of a treatment instrument inserted into an insertion channel for the treatment instrument that the endoscope includes, in accordance with necessity.
Further, an endoscope that is used in the industrial field enables inspection such as observation of flaws, corrosion and the like of sites to be examined in an object, and various kinds of treatments, by an elongated insertion portion of the endoscope being inserted into the inside of a jet engine and the inside of the object such as piping of a factory.
Here, a configuration is known, in which an action portion, for example, a bending portion that is bendable in a plurality of directions is provided at the insertion portion of an endoscope.
A bending portion enhances advancability of the insertion portion in a curved portion in a conduit, and in addition, makes an observation direction of an observation optical system variable, that is provided at a distal end portion located at a distal end side in an insertion direction from the bending portion (hereinafter, simply called a distal end side).
Usually, the bending portion provided at the insertion portion of an endoscope is configured to be bendable in four directions of, for example, an up, a down, a left and a right by a plurality of bending pieces being connected along an insertion direction of the insertion portion.
More specifically, the bending portion is made bendable in any of the directions of an up, a down, a left and a right by a pulling operation being performed from the operation portion for any of four wires that are moving members that have distal ends fixed to a bending piece that is located at the most distal end side among the bending pieces, are inserted through the inside of the insertion portion, and are movable forward and rearward in the insertion direction.
Note that the reason why only the bending portion bends with pulling of the wire is that in the insertion portion, outer peripheries of the wires in the soft flexible tube portion that is located at a proximal end side in the insertion direction from the bending portion (hereinafter, simply called a proximal end side) is covered with a guide sheath or the like in a state in which a distal end and a proximal end in the insertion direction are fixed to an inside of the flexible tube portion. More specifically, this is because even if the wire is pulled, the guide sheath resists a compressive force along an extending direction of the guide sheath that is added to the guide sheath.
Incidentally, a bending portion is more capable of making small turns as a length thereof in the insertion direction formed to be shorter, namely, as a bending radius thereof is smaller. Therefore, it is advantageous because passability of the distal end portion of the insertion portion with respect to a curved portion in a conduit is enhanced, and in addition thereto, the observation optical system provided at the distal end portion can be easily moved close to a site to be examined.
This is because, for example, in the case of an endoscope for medical use, if the bending portion is formed to be long, the distal end portion hits a curved portion in the curved portion of a large intestine and a visual field is easily lost, when the endoscope is inserted into the large intestine. Namely, this is because as the bending portion is shorter, the distal end portion is less likely to hit an intestinal wall in the curved portion. Note that in order to make the length of the bending portion short, the number of bending pieces that are connected can be decreased.
Furthermore, in the case of the endoscope for medical use, the method is generally used, that linearizes a curved portion by drawing the proximal end side of an insertion portion in a state in which a distal end portion and a bending portion are hooked on tissue in a body cavity after the distal end portion passes the curved portion, and thereafter, pushes the insertion portion from the proximal end side to cause the bending portion to pass through the curved portion.
In the light of the problem as above, Japanese Patent Application Laid-Open Publication No. 2008-253744 discloses the configuration in which two bending portions are provided at the distal end side of an insertion portion as the first bending portion and the second bending portion, and by an elastic covering member having a thickness, the second bending portion is more rigid than the first bending portion in the proximal end side from the first bending portion. According to the configuration, the configuration is included, in which when a wire is pulled with a small force, only the first bending portion can be bent, and when the wire is pulled with a large force, the second bending portion as well as the first bending portion can be bent, and thereby the length of the bending portion can be made variable in accordance with a situation.
Furthermore, Japanese Patent Application Laid-Open Publication No. 2005-185526 discloses the configuration in which two shape memory alloys with rigidity increasing with supply of a current are provided along the insertion direction, in the bending portion located at the distal end side of the insertion portion.
In the configuration, when only the distal end side of the bending portion is desired to be bent on one hand, a current is supplied to the shape memory alloy located at the proximal end side to enhance rigidity of the proximal end side of the bending portion, whereby the proximal end side of the bending portion is not bent, but only the distal end side is bent, with pulling of a wire. On the other hand, when the bending portion is desired to be bent from the proximal end side, a current is supplied to the shape memory alloy located at the distal end side to enhance rigidity of the distal end side of the bending portion, whereby the distal end side of the bending portion is not bent, but only the proximal end side is bent, with pulling of the wire.
Further, Japanese Patent Publication No. 4856289 discloses in the configuration provided with the first bending portion and the second bending portion at the distal end side of the insertion portion, the configuration in which the outer peripheries of four wires inserted through the inside of the insertion portion are respectively covered with inner guide sheaths that are moving members movable forward and rearward in the insertion direction, distal ends in the insertion direction of the inner guide sheaths (hereinafter, simply called distal ends) are fixed to the distal end of the second bending portion, and proximal ends in the insertion direction of the respective inner guide sheaths (hereinafter, simply called proximal ends) are simultaneously switchable to a fixed state and an unfixed state by a fixation switching member. Further, Japanese Patent Publication No. 4856289 discloses the configuration in which the outer peripheries of the respective inner guide sheaths are respectively covered with outer guide sheaths, distal ends of the outer guide sheaths are fixed to the distal end of a flexible tube portion, and the proximal ends of the outer guide sheaths are fixed to a rear side from a proximal end of the flexible tube portion.
The fixation switching member described in Japanese Patent Publication No. 4856289 is configured by a base material and two sandwiching contact members, and has a configuration that moves the two sandwiching contact members respectively in a vertical direction orthogonal to the insertion direction toward the base member with use of a link mechanism, and inserts to pinch the proximal ends of the respective inner guide sheaths in between the two sandwiching contact members and the base material to thereby fix the proximal ends of the respective inner guide sheaths.